The December 2015 Release contains the following enhancements:
- Ability to set a default billing contact. This is useful for accounts that you invoice on a regular basis.
- Payment rollup on Opportunity.
- More options when defining payment plans.
- When creating an invoice, contact being associated with the account is now optional. You can use a contact that is not under the account.
- Support for Card-Present transactions.
- Bug fixes.